Radiolytic advantages

Addition of sodium polyphosphate appreciably altered the rate constants for reactions (19)—(21) and stabilized the small non-metallic silver clusters [512, 513]. Advantages of the steady-state and pulse-radiolytic approaches to silver-cluster formation are manifold. Firstly, experimental conditions can be precisely adjusted such that the reactive species is exclusively e or, alternatively, that it is a known alcohol radical. Secondly, the concentration of the reducing species (the number of reducing equivalents generated) is readily calculable. Thirdly, in time-resolved experiments, rate constants for the individual reaction steps can be determined by monitoring absorption and/or conductivity changes. These latter determinations permitted the assessment of agglomeration numbers [512,513]. 

Preparation of non-aqueous dispersions of colloidal silver by phase transfer has been described [51] and advantage has been taken to form monodisperse, 7.0-nm-diameter silver particles by simultaneously reducing Ag+ and partially oxidizing Agn particles (radiolytic push-pull reduction method) [52]. The surface chemistry of nanosized silver particles has continued to receive attention [53, 54],... 

In radiolytic studies, C02 is often used with some advantage the superoxide radical, 02 [reaction (26) Chap. 8.4], as a precursor of... 

In the Pt-doped hexagonal mesophase formed from CPCI (cetyl pyridinium chloride), platinum ions are adsorbed at the surface of the surfactant cylinders. They are reduced radiolytically into a metal layer as a nanotube of around 10 nm diameter and a few hundred nm long (Fig. 3f). Extraction of all these nanostructures is achieved by dissolution of the soft template using alcohol. This possible easy extraction constitutes a marked advantage over the synthesis in hard templates, such as mesoporous silica or carbon nanotubes, the dissolution of which is more hazardous for the metal nanostructures. 

Ionic reactions in ethyl chloride have been studied by both mass spectrometric and radiolysis techniques. The radiolysis mechanism advanced on the basis of our experimental observations indicates that the major radiolytic reaction mode in this system is excited neutral molecule decomposition. While the role of ionic reactions in the radiolysis therefore appears to be relatively minor, it was possible to establish a good correlation between the predictions of the mass spectrometric studies with respect to ionic intermediates and the participation of such ions in the radiolytic reaction scheme. These results emphasize the advantages of combining the techniques used here to obtain a complete description of the reactive system. 

The coolant finally selected is a partially hydrogenated mixture of terphenyls which is liquid down to 273 K. This advantage outweighs the somewhat higher radiolytic decomposition rate than that of pure ter-phenyl (72), Radiolytic and pyrolytic decomposition lead to a coolant... 

A detailed piece of earher work was also concerned with muon end-of-track radiolytical processes in acetone [23], The muonated species observed on a microsecond time scale is the radical formed formally by Mu addition to the carbonyl oxygen. It was shown that two-thirds of the radicals were indeed formed by addition of Mu on a time scale of 0.1 ns. The remaiiting one-third did not involve a Mu precursor and was instead formed by direct combination of a track electron with a muon-acetone complex, or of a muon with an acetone anion, on a time scale of about 3 ns. This conclusion was based on an analysis of the observed initial phases of muon precession as a function of the apphed magnetic field, and it takes advantage of the ct that the muon in a diamagnetic environment precesses in the opposite direction, and with a different precession fi-equency compared with the muon in Mu. 

The use of gamma radiation for the Initiation of free radical chain reactions In liquids offers several advantages over the more conventional methods of initiation. With this technique radical reactions that are not readily accessible by other methods can be studied. Because of the wide temperature range within which radiolytic initiation can be applied this method allows an accurate determination of Arrhenius parameters and therefore can bring better understanding and deeper insight to the factors that control the rates and mechanism of free radical reactions. 

At Soreq gamma radiolysis of liquid systems has been used in studies of various free radical chain reactions. The purpose of this work is to illustrate and demonstrate, through a survey of those studies, the advantages and limitations of the radiolytic method ... 

The advantages and limitations of radiolytic initiation. Radiolytic initiation is particularly useful in kinetic studies of liquids phase free radical chain reactions. The advantages of this technique can best be seen by comparing it with other commonly used methods of initiation, photolysis and thermal decomposition of initiators. 

Obviously, MeSO concentration can be estimated from the rate of formation of its termination products. Unfortunately, these products are known to be unstable and therefore their determination is difficult. The advantage of radiolytic systems of a constant and known rate of Initiation can again be utilized to derive the concentration of MeS02. radicals. This estimation is based on the assumption that IMeS02] lMeG and lRS02ll lR] so that... 

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